From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Correcting errors in the dimensional comparison of sample spanners, providing a new table with jaw and handle thicknesses.
| Identifier | ExFiles\Box 20\8\ Scan039 | |
| Date | 14th June 1923 | |
| X1027 E.{Mr Elliott - Chief Engineer} c. G.J. c. Hs.{Lord Ernest Hives - Chair} c. BP. BY12-P14.6.23. SAMPLE SPANNERS TO LeC.1645. X1027 Referring to E2/M12623, one obvious error has been made in making the comparisons. Heading number 2, W.W. size does not represent the thicknesses of the jaw, but the thicknesses of the handle, and as a matter of fact on all the forgings except one the thickness of the handle does not vary more than .025" from the dimension actually called for on the LeC. drawing. In order to make a correct comparison five columns are necessary, as given below;- Spanner size. Jaw Handle as drg. as model. as drg. as model. 1/2" .375 .412 .300 .306 7/16" .325 .368 .250 .270 3/8" .275 .304 .225 .221 5/16" .250 .295 .200 .220 1/4" .200 .225 .175 .190 1 BA. .175 .208 .150 .175 2 BA. .156 .192 .125 .152 3 BA. .125 .170 .100 .125 5 BA. .125 .170 .100 .150 As an example of the error your figures introduced I would like to point out on the 1/2" spanner that the thickness of the head instead of being .300" as you quote is .375", so that as the actual spanner measures .415" the error is .040" in thickness and not .115" as given on your table. contd. | ||